An investigation will be made of the genetic and cytogenetic aspects of cancer in an inbred human isolate, the Hutterites. Two field trips will be made to selected colonies (communal farms). The purposes of these trips will be: (1) to ascertain the types and frequencies of cancer through the examination of local death and medical records, and through personal interviews and physical examinations; and (2) the collection of blood samples for chromosomal and other studies. A detailed genetic and cytogenetic investigation will then be made of families in which cancer is found. Since the Hutterites share a uniform environment, the existence of familial aggregates of cancer in this population is more likely demonstrative of genetic etiology than of intrafamilial environmental homogeneity. The records already collected for this population will serve as the base for the proposed studies. These records include extensive pedigrees, blood groups and serum protein classifications, and information on certain variables of medical interest. The data already collected will also be useful for linkage studies. Because of the inbred nature of the group, and the fact that the coefficient of inbreeding has already been calculated for all marriages, emphasis will be placed on a search for recessive mutant gene control over cancer and over factors predisposing to cancer, such as those altering the mitotic process.